Protected extendable joint



. Jan. 27,1970 ED 0. SEABOURN I PROTECTED EXTENDABLE JOINT Filed Feb. 16, 1968 INVENTOR.

E. O. SEABOURN FIG. 2 v

A 7' TORNE VS United States Patent 3,492,028 PROTECTED EXTENDABLE JOINT Ed 0. Seabourn, Stavanger, Norway, assignor to Phillips Petroleum Company, a corporation of Delaware Filed Feb. 16, 1968, Ser. No. 706,176 Int. Cl. F161 55/00, 11/12 US. Cl. 285-45 6 Claims ABSTRACT OF THE DISCLOSURE The vertical motion of a floating oil rig drilling ship due to wave action made it desirable to utilize an extendable ioint to maintain the position of the drill bit while preventing the breaking of the drill string. A suitable extendable joint for this purpose is the device called a bumper sub. The bumper sub has an upper sleeve with the same outside diameter as the drill string tubing and a lower sleeve of reduced diameter which telescopes within the upper sleeve. When the lower sleeve is at least partially extended, it forms a weak link in the drill string due to its reduced diameter. This weakness can become critical in drilling the initial large diameter hole where the bumper sub has no support against lateral bending. Under these circumstances the occurrence of a sufficient lateral force can bend or even break the lower sleeve. In addition, the design of some bumper subs permits abrasive material to enter the sub when in an extended position. Also, the bumpersubs can be jammed by unconsolidated rock or other material becoming wedged in the open joint.

Accordingly, it is an object of the invention to protect an extendable joint against lateral bending. It is an object of the invention to provide a protecting sleeve for a bumper sub. An object of the invention is to minimize entry of abrasive material into an extendable joint. Another object of the invention is to prevent rock or other material from being wedged in an open joint of a bumper sub.

Other objects, aspects and advantages of the invention will be apparent from a study of the specification, the drawings and the appended claims to the invention.

It has been discovered that the foregoing objects can be achieved and the disadvantages of the prior system avoided by utilizing an outer sleeve which is longer than the upper sleeve, the outer sleeve being of larger diameter to encompass the bumper sub and being attached to the upper end of the bumper sub. Where a plurality of bumper subs is utilized, the outer sleeve is longer than the series of bumper subs in the fully extended position so that the exposed lower sleeves are completely within the outer sleeve.

In the drawings, FIGURE 1 is an elevation view, partly in cross section of a bumper sub provided with an outer protective sleeve in accordance with the invention, the bumper sub being partially extended, and FIGURE 2 is an elevation view, partly in cross section of the device of FIGURE 1 with the bumper sub fully extended.

Referring now to the drawings in detail, the protected bumper sub 11 is connected between two sections of drill pipe 12 and 13. The bumper sub has an upper sleeve Patented Jan. 27, 1970 14 provided with a top end screw socket 15, adapted for threaded engagement with the male screw plug 16 on the bottom end of adapter sub 17. Similarly, adapter sub 17 is provided with a topend screw socket 18, adapted for threaded engagement with the male screw plug 19 on the bottom end of drill pipe 12. Adapter sub 17 is provided with an axial passageway 21 to connect the interior of drill pipe 12 to the interior of upper sleeve 14. A bottom-end bushing 22 is screwed into the lower end of the bore of upper sleeve 14. Bushing 22 has a smaller internal diameter than the upper sleeve, thereby presenting a bumping shoulder 23.

The outer diameter of lower sleeve 24 is smaller than the internal diameter of upper sleeve 14, permitting lower sleeve 24 to telescope within upper sleeve 14. Lower sleeve 24 is provided with a plurality of longitudinal keyways 25 in the exterior surface thereof. Bushing 22 is provided with a corresponding plurality of feathers, or keys, 26 which extend into the keyways 25. The keys 26 in keyways 25 permit the lower sleeve 24 to reciprocate axially with respect to upper sleeve 14, but prevent relative rotation of the upper and lower sleeves.

The lower end of lower sleeve 24 is provided with a section 27 of increased diameter, preferably the same external diameter as the drill pipe 13 and the upper sleeve 14. Section 27 is provided with a male screw plug 28 on the bottom end thereof adapted for threaded engagement with the top end screw socket 29 of drill pipe 13. Section 27 has an axial passageway 31 therethrough for communication between the interior of drill pipe 13 through the interior of sleeves 14 and 24 and adapter sub 17 to the interior of drill pipe 12.

In accordance with the invention, adapter sub has a section 32 of enlarged diameter having screw threads on the exterior thereof. An outer protective sleeve 33, having an internal diameter greater than the maximum external diameter of the bumper sub, is internally threaded at its upper end for threaded engagement with section 32. The sleeve 33 has a length sufiicient to extend below section 27 in the fully extended position for the bumper sub, as illustrated in FIGURE 2. For convenience, the lower portion of sleeve 33 has been omitted in FIGURE 1. Where two or more bumper subs are connected together to increase the extension range, sleeve 33 is of sufiicient length to extend below the section 27 of the lowest bumper sub. As the external diameters of section 27, sleeve 14 is less than the internal diameter of protective sleeve 33, the lower sleeve 24 (and entire bumper subs, if more than one is utilized) can reciprocate within sleeve 33. The difference between the external diameter of the bumper sub and the internal diameter of the protective sleeve is sufficiently small to provide the desired protection against bending of the small diameter lower sleeve 24 during lateral forces. Generally, this difference will be less than two inches and preferably will be in the range of about inch to about /2 inch.

Sleeve 33 prevents loose rock in the borehole from entering the keyways 25 and jamming the bumper sub, thus preventing reciprocation. Similarly, sleeve 33 prevents any larger rocks in the borehole from engaging the lower shoulder of section 22 or the upper shoulder of section 27 and snagging or pinning the bumper sub in the borehole. The securement of casing 33 at its upper end to adapter sub 17 reduces the contact of abrasive material in the borehole fluid with the sliding surfaces of the upper and lower sleeves.

The following example is presented in further illustration of the invention, but should not be construed to unduly limit the invention. In one particular application, the upper end of adapter sub 17 had an external diameter of 7% inches, which was the same as that of drill pipes 12 and 13, upper sleeve 14 and section 27. The section 32 of adapter sub 17 was threaded to receive a metal sleeve 33 having an internal diameter of 7.92 inches and an external diameter of 8% inches. The bumper sub, from tip to tip, excluding the adapter sub, had a length of approximately 11 feet 6 inches in the fully closed, or retracted, position and a length of approximately 16 feet 6 inches in the fully elongated position. The outer sleeve 33 had a length in excess of 20 feet below the bottom of the adapter sub.

While the invention has been described in terms of upper sleeve 14 being the outer sleeve and lower sleeve 24 as being the inner sleeve, this can be reversed. While the invention has been described in terms of a specific bumper sub, other types of bumper subs and other extendable joints can be employed.

I claim:

1. Apparatus comprising an elongated extendable joint having an upper end, a lower end, and a fluid passageway along the longitudinal axis thereof, and having a fully elongated position and a retracted position; said extendable joint comprising an outer sleeve and an inner sleeve; said inner sleeve being telescopable within said outer sleeve from said fully elongated position to said retracted position; means for limiting the extension of said extendable joint; and a protective sleeve surrounding said extendable joint and connected at one end thereof to one of said upper and lower ends, the internal diameter of said protective sleeve being greater than the maximum outer diameter of said extendable joint; said protective sleeve having a length greater than the combined length of said outer sleeve and said inner sleeve when said inner sleeve is extended to said fully elongated position and positioned to extend beyond the upper and lower ends of said combined length of said outer sleeve and said inner sleeve when said inner sleeve is extended to said fully elongated position, to thereby protect said extendable joint against lateral bending forces.

2. Apparatus in accordance with claim 1 wherein said extendable joint is a bumper sub.

3. Apparatus in accordance with claim 1 wherein said outer sleeve is connected at its upper end to the bottom end' of an adapter sub and said protective sleeve is connected at its upper end to the bottom end of an adapter sub and said protective sleeve is connected at its upper end to said adapter sub to form the connection of said one end of said protective sleeve to said one of said upper and lower ends of said extendable joint.

4. Apparatus in accordance with claim 3 further comprising a drill string tubing connected at its lower end to the top end of said adapter sub, and conduit means connected to the lower end of said inner sleeve, said conduit means having an external diameter greater than the external diameter of said inner sleeve and less than the internal diameter of said protective sleeve.

5. Apparatus in accordance with claim 3 further comprising means for preventing relative rotation of said inner and outer sleeves.

6. Apparatus comprising an elongated extendable joint having an upper end, a lower end, and a fluid passageway along the longitudinal axis thereof, and having a fully elongated position and a retracted position; means for limiting the extension of said extendable joint; said extendable joint comprising an outer sleeve and an inner sleeve; said inner sleeve being telescopable within said outer sleeve from said fully elongated position to said retracted position; said outer sleeve being connected at its upper end to the bottom end of an adapter sub; means directly engaging said inner and outer sleeves for preventing relative rotation of said inner and outer sleeves; and a protective sleeve surrounding said extendable joint and connected at its upper end to said adapter sub, the internal diameter of said protective sleeve being substantially constant throughout and being greater than the maximum outer diameter of said extendable joint; said protective sleeve having a length greater than the length of said inner and outer sleeves and completely overlapping said inner and outer sleeves when said extendable joint is in said fully elongated position, to thereby protect said extendable joint against lateral bending forces.

References Cited UNITED STATES PATENTS 320,661 6/1385 Jarves 285302 X 2,664,271 12/1953 Arutunofi 285302 X 3,291,225 12/1966 Foran 285-302 X FOREIGN PATENTS 524,935 8/ 1940 Great Britain.

DAVID J. WILLIAMOWSKY, Primary Examiner D. W. AROLA, Assistant Examiner US. Cl. X.R. 285302, 330 

